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Trigeminal Nerve
The document provides a detailed overview of the trigeminal nerve, its anatomy, and functions, including the sensory and motor roots and their corresponding branches (ophthalmic, maxillary, and mandibular divisions). It describes the trigeminal ganglion's relationships with surrounding structures and the various sensory and motor functions each division serves. Additionally, it explores the associated branches, such as nasociliary and maxillary nerves, and their anatomical pathways and functions in innervating facial structures.
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Trigeminal Nerve
- 1. TRIGEMINAL NERVE DR AMITHA G,BDS, MDS ORAL AND MAXILLOFACIAL PATHOLOGY
- 2. TRIGEMINAL NERVE - Fifthcranial nerve - Have a large sensory root and a small motor root. - Motor root arises – arises from the lateral aspect of lower pons (cranially) the motor root cross the apex of the petrous temporal bone beneath the superior petrosal sinus, to enter the middle cranial fossa. - Sensory root – arises from the lateral aspect of lower pons (caudally).
- 3. TRIGEMINAL GANGLION - Sensoryganglion of fifth cranial nerve. - Homologous with the dorsal nerve root ganglia of spinal nerves. - All such ganglia are made of pseudounipolar nerve cells, with a T shaped arrangement of their process; one process arises from the cell body which then divides into a central and peripheral process. - Ganglion is cresentic or semilunar in shape with its convexity directed anterolaterally.
- 4. - 3 divisionsof trigeminal nerve emerge from this convexity. - Posterior concavity of the ganglion receives the sensory root of the nerve. - Situation and meningeal relations - Ganglion lies on the trigeminal impression, on the anterior surface of the petrous temporal bone near its apex. - It occupies a special space of dura matter called the trigeminal or Meckel’s cave. - There are 2 layers of the dura below the ganglion. - The cave is lined by pia arachnoid, so that ganglion along with the motor root of the trigeminal nerve is surrounded by CSF. - The ganglion lies at a depth of about 5cm from the preauricular point.
- 5. RELATIONS - Medially (a) internalcarotid artery (b) posterior part of cavernous sinus - Laterally - middle meningeal artery - Superiorly - parahippocampal gyrus - Inferiorly (a) motor root of trigeminal nerve (b) greater petrosal nerve (c) apex of the petrous temporal bone (d) foramen lacerum.
- 6. Associated root andbranches - Central processes of ganglion cells form the large sensory root of the trigeminal nerve which is attached to the pons at its junction with the middle cerebellar peduncle. - Peripheral processes of the ganglion cells form 3 divisions of the trigeminal nerve, namely ophthalmic, maxillary and mandibular. - Small motor root of the trigeminal nerve is attached to the pons superomedial to the sensory root. - It passes under the ganglion from its medial to the lateral side, and join the mandibular nerve at the foramen ovale.
- 7. OPTHALIMIC DIVISION Terminal branchesof Ophthalmic division of trigeminal nerve, are 1. Frontal Supratrochlear Supraorbital 2. Nasociliary Branch of ciliray ganglion 2-3 long ciliary nerves Posterior ethmoidal Infratrochlear Anterior ethmoidal 3. Lacrimal
- 8. LACRIMAL NERVE - Smallestof the 3 terminal branches of ophthalmic nerve - It enters the orbit through the lateral part of the superior orbital fissure and runs forwards along the upper border of the lateral rectus muscle in company with the lacrimal artery. - Anteriorly it receives communication from the zygomaticotemporal nerve, passes deep to the lacrimal gland and ends in the lateral part of the upper eyelid.
- 9. Supplies - Lacrimal gland,conjunctiva, upper eyelid. - Its own fibers to the gland are sensory. - Secretomotor fibers to the gland come from the greater petrosal nerve through its communication with zygomaticotemporal nerve.
- 10. FRONTAL NERVE - Isthe largest of the 3 terminal branches of the ophthalmic nerve. - Begins in the lateral wall of the anterior part of cavernous sinus. - It enters the orbit though the lateral part of the superior orbital fissure, and runs forwards on the superior surface of levator palpebrae superioris. - At the middle of the orbit it divides into small supratrochlear branch and large supraorbital branch.
- 11. NASOCILIARY NERVE - Oneof the terminal branches of the ophthalmic division of trigeminal nerve - Begins in the lateral wall of the anterior part of the cavernous sinus. - It enters the orbit through the middle part of the superior orbital fissure between the two divisions of the occulomotor nerve. - It crosses above the optic nerve from lateral to medial side along with ophthalmic artery and runs along the medial wall of the orbit between the superior oblique and the medial rectus. It ends at anterior ethmoidal foramen by dividing into the infratrochlear and anterior ethmoidal nerves.
- 12. - Its branchesare as follows 1. A communicating branch to ciliary ganglion – forms the sensory root of the ganglion. It is often mixed with the sympathetic root. 2. Two to three long ciliary nerves run on the medial side of the optic nerve, pierce the sclera, and supply sensory nerves to the cornea, the iriss and the ciliary body. They also carry sympathetic nerves to dilator papillae. 3. Posterior ethmoidal nerve – passes through the posterior ethmoidal foramen and supplies the ethmoidal and sphenoidal air sinuses. It is frequently absent.
- 13. 4. Infratrochlear nerve– smaller terminal branch of the nasociliary nerve given off at the anterior ethmoidal foramen. It emerges from the orbit below the trochlear for the tendon of the superior oblique and appears on the face above the medial angle of the eye. It supplies the conjunctiva, the lacrimal sac and caruncle, the medial ends of the eyelids and the upper half of the external nose.
- 14. 5. Anterior ethmoidalnerve – is the larger terminal branch of the nasociliary nerve. It leaves the orbit by passing through the anterior ethmoidal foramen. It appears for a very short distance, in the anterior cranial fossa, above the cribriform plate of the ethmoid bone. It then descends into the nose through a slit at the side of the anterior part of the crista galli. In the nasal cavity, it lies deep to the nasal bone. It gives off 2 internal nasal branches medial and lateral to the mucosa of the nose. Finally, it emerges at the lower border of the nasal bone as the external nasal nerve which supplies the skin of the lower half of the nose.
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- 16. MAXILLARY NERVE - Arisesfrom the trigeminal ganglion - Runs forward in the lateral wall of the cavernous sinus below the ophthalmic nerve and leaves the middle cranial fossa by passing through the foramen rotandum . - Next, the nerve crosses the upper part of the pterygopalatine fossa, beyond which it is continues as the infraorbital nerve. - In the pterygopalatine fossa the nerve is intimately related to the pterygopalatine ganglion, and gives off zygomatic and posterior superior alveolar arteries. - The posterior superior alveolar nerve enters the posterior surface of the body of the maxilla, and supplies the three upper molar teeth and the adjoining part of gum.
- 17. PTERYGOPALATINE GANGLION - Isthe largest parasympathetic peripheral ganglion. - It serves as a relay station for secretomotor fibers to the lacrimal gland and to the mucous glands of the nose, paranasal sinuses the palate and pharynx. - Topographically relatedo the maxillary nerve, but functionally connected to the facial nerve through its greater petrosal branch. - Location – the flattened ganglion lies in the pterygopalatine fossa just below the maxillary nerve, in front of the pterygoid canal and lateral to the sphenopalatine foramen.
- 18. Connections 1. Motor orparasympathetic root of the ganglion - By the nerve of pterygoid canal. - It carries preganglionic fibers that arise from neurons present near the superior salivatory and lacrimatory nuclei, and pass through the nervus intermedius, the facial nerve, the geniculate ganglion, greater petrosal nerve, nerve of pterygoid canal, to reach the ganglion. - The fibers relay in the ganglion. - Post ganglionic fibers arise in the ganglion to supply secretomotor nerves to the lacrimal gland and to mucous gland of the nose, paranasal sinuses, palate and nasopharynx.
- 19. 2. Sympathetic root -Is also derived from the nerve of pterygoid canal. - It contains postganglionic fibers arising in the superior cervical sympathetic ganglion which pass through the internal carotid plexus, deep petrosal nerve, nerve of pterygoid canal to reach the ganglion . - The fibers pass through the ganglion without relay and supply vasomotor nerves to the mucous membrane of the nose, the paranasal sinuses, palate an dnasopharynx. 3. Sensory root - Comes from the maxillary nerve - Its fibers pass through the ganglion without relay. - They emerge in the branches
- 20. Branches - The branchesof the ganglion are actually branches of he maxillary nerve. - They also carry parasympathetic and sympathetic fibers which pass through the ganglion. - The branches are a. Orbital branches Pass through the inferior orbital fissure Supply the periosteum of orbit and orbitalis muscle b. Palatine branches The greater or anterior palatine nerve descends through the greater palatine canal, and supplies the hard palate and the lateral wasll of the nose, i.e inferior conchaand adjoining meatuses. The lesser or middle and posterior palatine nerves supply the soft palate and the tonsil.
- 21. c. Nasal branches Enterthe nasal cavity through the sphenopalatine foramen. The lateral posterior superior nasal nerves (about 6 in number), supply the posterior part of the roof of the nose and of the nasal septum. The largest oof these nerves are called nasaopalatine nerve, which descends upto the anterior part of the hard palate through the incisive foramen. d. Pharyngeal branch Passes through the palatogingival canal and supplies the part of the nasopharynx behind the auditory tube
- 22. e. Lacrimal branch Thepostganglionuc fubers pass back into the maxillary nerve to leave it through its zygomatic nerve and its zygomatic temporal branch. It is a communicating branch to lacrimal nerve to supply secretomotor fibers to the lacrimal gland. Preganglionic fibers have their origin in the lacrimatory nucleus.
- 23. INFRAORBITAL NERVE - Itis the continuation of the maxillary nerve. - It enters the orbit through the inferior orbital fissure. - It then runs forwards on the floor of the orbit or the roof of the maxillary sinus, at the first in the infraorbital groove and then in the infraorbital canal remaining outside the periosteum of the orbit. - It emerges on the face through the infraorbital foramen and terminates by dividing into palpebral, nasal and labial branches. - The nerve is accompanied by the infraorbital branch of the third part of the maxillary artery and the accompanying vein.
- 24. Branches a. Middle superioralveolar nerve b. Anterior superior anterior superior alveolar nerve arise in the infraorbital canal and runs in a sinuous canal having a complicated course in the anterior wall of the maxillary sinus. It supplies the upper incisor and canine teeth, the maxillary sinus and the antero inferior part of the nasal cavity. c. Terminal branches – palpebral, nasal and labial – supply a large area of the skin on the face. They also supply the mucous membrane of the upper lip and cheek.
- 25. ZYGOMATIC NERVE - Itia branch of the maxillary nerv, given off in the pterygopalatine fossa. - It enters the orbit through the lateral end of the inferior orbital fissue, and runs along the lateral wall, outside the periosteum, to enter the zygomatic bone. - Just before or after entering the bone it divides into its 2 terminal branches, the zygomaticofacial and zygomatiotemporal nerves which supply the skin of the face and of the anterior part of the temple. - The communicating branch to the lacrimal nerve, which contains secretomotor fibers to the lacrimal gland, may arise either from the zygomatic or the zygomaticotemporal nerve, and runs in the lateral wall of the orbit.
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- 27. MANDIBULAR NERVE - Isthe largest of the 3 divisions of the trigeminal nerve - It is the nerve of first branchial arch - It has both sensory and motor fibers - It supplies all structures derived from the mandibular or first branchial arch
- 28. Course and relations -Mandibular nerve begins in the middle cranial fossa through a large sensory root and a small motor root. - Sensory root arises from the lateral part of the trigeminal ganglion, and leaves the cranial cavity through the foramen ovale. - Motor root lies deep to the trigeminal ganglion and to the sensory root. - It also passes through the foramen ovale to join the sensory root just below the foramen thus forming the main trunk. - The main trunk lies in the infratemporal fossa, ON the tensor veli paltini, DEEP to the lateral pterygoid. - After a short course, the main trunk divides into a Small anterior trunk and a
- 29. Branches - From maintrunk a. Meningeal branch b. Nerve to medial pterygoid - From the anterior trunk Sensory branch a. Buccal nerve Motor branch a. Masseteric b. Deep temporal nerve c. Nerve to lateral pterygoid - From the posterior trunk a. Auriculotemporal b. Lingual c. Inferior alveolar nerves
- 30. Meningeal branch ornervus spinosus - Course - Meningeal branch enters the skull through the foramen spinosum with the middle meningeal artery - Supplies – dura matter of middle cranial fossa Nerve to medial pterygoid - Origin – arises close to the otic ganglion - Supplies - medial pterygoid from its deep surface. - This nerve gives a motor root to the otic ganglion which does not relay and supplies tensor veli palatine and tensor tympani muscles.
- 31. BUCCAL NERVE - Onlysensory branch of the anterior division of the mandibular nerve. - It passes between the 2 heads of the lateral pterygoid, runs downwards and forwards - Supplies – skin and mucous membrane related to buccinator. Also supplies buccal aspect of gums of the molar and premolar teeth of both maxillary and mandibular teeth.
- 32. MASSETRIC NERVE - Emergesat the upper border of the lateral pterygoid just in front of the TMJ, passes laterally through the mandibular notch in company with the massetric vessels and enters the deep surface of the masseter. - It also supplies the TMJ
- 33. DEEP TEMPORAL NERVES -There are 2 deep temporal nerves a. Anterior b. Posterior - They pass between the skull and the lateral pterygoid and enter the deep surface of the temporalis. - Anterior nerve is often a branch of the buccal nerve. - Posterior nerve may arise in common with the massetric nerve.
- 34. NERVE TO LATERALPTERYGOID - Enters the deep surface of the muscle. - It may be an independent branch or may arise in common with the buccal nerve.
- 35. AURICULOTEMPORAL NERVE Origin - Arisesby 2 roots Course - 2 roots run backwards, encircling the middle meningeal artery - Unites to form a single trunk - Then continues backwards between the neck of the mandible and the sphenomandibular ligament, above the maxillary artery - Behind the neck of mandible it turns upwards and ascends on the temple behind the superficial temporal vessels.
- 36. Supplies - Auricular part– supplies the skin of the tragus, upper parts of the pinna, the external acoustic meatus, tympanic membrane. (note:- the lower parts of these regions are supplies by the great auricular nerve and the auricular branch of the vagus nerve) - Temporal part – supplies the skin of the temple. - Articular branches – to TMJ - In addition secretomotor supply to the parotid gland (and also sensory)
- 37. LINGUAL NERVE - Isone of the 2 terminal branches of the posterior division of trigeminal nerve. Orgin - Begins 1 cm below the skull. Course and relations - It runs first between the tensor veli palatini and the lateral pterygoid and then between the lateral and medial pterygoid. - 2cm below the skull it is joined by the chorda tympani. - Emerging at the lower border of the lateral pterygoid, the nerve runs downwards and forwards between the ramus of the mandible and the medial pterygoid.
- 38. - Next itlies in direct contact with the mandible, medial to the third molar tooth between the origins of superior constrictor and the mylohyoid muscle. - It soon leaves the gums and runs over the hyoglossus deep to the mylohyoid. - Finally lies on the surface of the genioglossus deep to mylohyoid. - Here it winds round the submandibular duct and divides into terminal branches.
- 39. Supplies - Sensory tothe anterior 2/3rd of the tongue and to floor of the mouth. - However, fibers of chorda tympani (branch of facial nerve) which is sceretomotor to the submandibular and sublingual glands and gustatory to the anterior 2/3rd of the tongue, are also distributed through this lingual nerve.
- 40. INFERIOR ALVEOLAR NERVE -Is the largest terminal branch of the posterior division of the mandibular nerve. - Runs vertically downwards lateral to the spenomandibular ligament and medial pterygoid. - Enters the mandibular foramen and runs in the mandibular canal. - It is accompanied by inferior alveolar artery. Branches
- 41. a. Mylohyoid branch -Arises just before the inferior alveolar nerve enters the mandibular foramen. - Contains all the motor fibers of posterior division - Pierces the spenomandibular ligament with the mylohyoid artery, runs in the mylohyoid groove - Supplies the mylohyoid muscle and the anterior belly of the digatsric.
- 42. b. Branches inthe mandibular canal – inferior dental plexus - While running in the mandibular canal the inferior alveolar nerve gives branches that supply the lower teeth and gums. (molar and premolar teeth and gums) c. Mental nerve - Emerges at the mental foramen - Supplies the skin of the chin and the skin and mucous membrane of the lower lip. d. Incisive branch - Its incisive branch supplies the labial aspect of the gums of canine and incisor teeth.
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